(a) Technical Field
The present invention relates to a display device including a touch sensor and a driving method thereof, and more particularly, to a curved display device including a touch sensor and a driving method thereof.
(b) Description of the Related Art
A display device such as a liquid crystal display (LCD), an organic light emitting diode (OLED) display, and an electrophoretic display includes a field generating electrode and an electro-optical active layer. For example, the OLED display includes an organic emission layer as the electro-optical active layer. The field generating electrode is connected to a switching element such as a thin film transistor to receive a data signal, and the electro-optical active layer converts the data signal into an optical signal to display an image.
Recently, such a display device may include a touch sensing function which can interact with a user in addition to a function of displaying the image. The touch sensing function is to determine touch information such as whether an object touches or approaches a screen and a touch position thereof by sensing a change in pressure, charges, light, and the like which are applied onto the screen in the display device, when the user writes a text or draws a figure by touching or approaching the screen with a finger or a touch pen. The display device may receive an image signal based on the touch information to display an image.
The touch sensing function may be implemented by a touch sensor. The touch sensor may be classified into various types such as a resistive type, capacitive type, electro-magnetic (EM) type, and optical type.
Among the different types of touch sensors, the capacitive type touch sensor includes a plurality of touch electrodes that may transfer sensing signals. The touch electrode may form another touch electrode and a sensing capacitor (mutual-capacitor type), and form a sensing capacitor together with an external object (self-capacitor type). When a conductor such as a finger approaches or touches the touch sensor, a change is generated in the capacitance and/or the amount of charge in the sensing capacitor to determine whether a touch exists or not, a position of the touch, and the like.
A plurality of touch electrodes is disposed in a touch sensing region where a touch may be sensed to be connected to a plurality of touch wires transferring sensing signals. The touch wires may be positioned inside the touch sensing region and disposed in a non-sensing region around the touch sensing region. The touch wire may transfer a sensing input signal to the touch electrode or transfer a sensing output signal of the touch electrode generated according to a touch to a touch driver.
The touch sensor may be embedded in the display device (in-cell type), directly formed on an outer surface of the display device (on-cell type), or used by attaching a separate touch sensor unit to the display device (add-on cell type). The display device including the touch sensor determines information regarding whether a finger or a touch pen of the user approaches a screen and a touch position thereof to display images.
Generally, when a viewer views a flat panel display device, a viewing distance from the viewer to the center of the display device and a viewing distance from the viewer to the edge of the display device are different from each other. This difference in viewing distances causes a distortion in the image. In order to reduce image distortion and increase immersion in image, recently, a display panel of the display device is concavely or convexly curved. The display panel of the curved display device may be curved along at least one direction. Further, a curvature radius representing a bending degree may also vary according to the display device and a position of the display panel even in one display device.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.